1. Field of the Invention
This invention relates to a new and improved hand held pressure regulating and monitoring device, and is more particularly concerned with a device especially useful for regulating and monitoring pressure within a chamber such as an inflatable cuff forming a part of a medical apparatus, although it will be apparent that the device has wider utility.
Merely by way of example, it may be mentioned that during certain types of surgical procedures, anesthetic is administered to a patient by using an endotracheal tube having an inflatable cuff which is inflated by source of pressurized air. When the cuff is properly inflated, the endotracheal tube is restrained against slippage by the pressure of the cuff against the mucosal wall of the trachea.
Even though the cuff is made from materials impervious to air, certain types of anesthetics are capable of passing through the walls of the cuff, thereby increasing the gas pressure therein. Often this increase in gas pressure exerted by the over-inflated cuff of the endotracheal tube can result in damage to the mucosal wall of the trachea, which in some instances may be irreversible. Consequently, it is extremely important that the cuff pressure be maintained at an as nearly as practicable optimum value, e.g. approximately 25 mmHg.
2. Prior Art
In order to monitor the cuff pressure, mechanical or mercury manometers have heretofore been used. Those devices are frequently cumbersome due to their size and they occupy valuable space within an operating room, recovery room or even in a patient's room. They also can be a serious distraction during critical operating procedures. Such manometers also contain a large amount of dead air space in the connecting tubes, and hence pressure readings are frequently inaccurate.
A significant improvement is disclosed in the pending application of John Pistillo Ser. No. 461,267 filed Jan. 26, 1983 and assigned to the present applicant. The device and method disclosed in that application are adapted to be applied to the tube by which the inflatable cuff is inflated, after the tube has been disconnected from an air or other gas source under pressure. The device of the prior application provides a hand held pressure monitoring device and which has the capability of modifying the air pressure in the cuff within a rather limited range, and is not adapted to provide the initial or basic cuff inflating air pressure.